Last week, investigators studying methane leakage levels in Manhattan reported alarming preliminary findings. The gas industry and Con Edison estimate 2.2% leakage in its distribution systems, and at leakage above 3.2%, according to the Environmental Defense Fund, natural gas ceases to have any climate advantage over other fossil fuels. But the study found an average cumulative leakage of over 5% in natural gas production and delivery. At these levels, natural gas—93% of which is methane—has a far more potent greenhouse gas impact than burned coal or oil, the authors stated.

"The reports offer the most rigorous analysis of rate loss” to date, Al Appleton, former Commissioner of the NYC DEP, told Alternet, representing a "serious environmental reality.” The study was conducted by Gas Safety, Inc of Southborough, MA, for Damascus Citizens for Sustainability, an Upper Delaware Valley environmental organization that has been at the forefront of the anti-fracking activity in the Marcellus Shale.

When burned, methane natural gas produces CO2 but at half the level of burned coal or oil, a fact that has won natural gas the reputation as the cleanest fossil fuel. In the atmosphere, however, methane (CH4), the principal ingredient of natural gas, is a powerful greenhouse gas, like CO2 absorbing infrared radiation from the earth and warming the planet. Indeed by weight, and over time (100 years), methane warms 20 times more than carbon dioxide.

Gas Safety, Inc. recorded actual emissions data during a 160-mile road trip of Manhattan streets.The novel leak surveyor system included a cavity ring-down spectrometer combined with a GPS system and computer control system. Installed in an automobile with an air sampling line mounted over the rear bumper, (with the inlet facing down approximately one foot above the pavement surface, and the GPS antenna on the roof), the instrument measures and records methane levels in the air above the pavement with an accuracy of a few parts per billion about 4 times per second. The onboard GPS system simultaneously records the location of the instrument as sampling occurs. The survey revealed many leaks, some intense, and few readings at expected methane levels.

According to Dr. Bryce Payne, one of the report’s authors, “The methane leakage in the system serving NYC through ConEd is likely already at a level where the methane leaked has as much, or more, climate impact as the remaining approximately 95% of the gas that is actually usefully burned by consumers in NYC.” The report states that “the loss of even a few percent of gas during production, transport, distribution and utilization is critically important to management and planning of present and future national and international energy supply and utilization systems.”

Widespread hydraulic fracturing of deep gas shale deposits makes natural gas not only plentiful but relatively cheap, with almost a third of the nation’s electricity now gas generated. National awareness of the dangers of fracking—from groundwater contamination to air pollution to earthquakes to the devastation of the landscape and home values—has skyrocketed, leaving both industry and government scurrying to assure that fracking is safe.

The petroleum industry has tried to rebut claims of methane migration demonstrated perhaps most dramatically by an ignited kitchen faucet in the documentary film Gasland. And more recently, methane in contexts other than fracking has come under scrutiny.

The study of fugitive emissions of natural gas in Manhattan was undertaken by DCS in order to enhance understanding of gas distribution in relation to global climate change. The study’s preliminary findings suggest that due to widespread leakage during extraction, transport and delivery, natural gas’s carbon footprint is vast and growing. "Many saw natural gas as the the bridge fuel to a renewable energy future,” DCS's Barbara Arrindell told Alternet, “but the new report is confirming that it's a dangerous bridge to nowhere.”

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Nora Eisenberg's work has appeared in the Village Voice, Tikkun, the Los Angeles Times, the Nation, and the Guardian UK. Her most recent novel, "When You Come Home" (Curbstone, 2009), explores the legacy of the 1991 Gulf War.